&algmult - Maple Help
For the best experience, we recommend viewing online help using Google Chrome or Mozilla Firefox.

Online Help

All Products    Maple    MapleSim


DifferentialGeometry[algebraic operations]

addition, subtraction, scalar multiplication, wedge product, tensor product

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

A &plus B - add two vectors, differential forms or tensors

A &minus B- subtract one vector, differential form or tensor from another

A &mult B - multiply a Maple expression by a vector, differential form or tensor

A &wedge B- form the wedge (or skew) product of a pair of differential forms or multi-vectors

A &tensor B- form the tensor product of a pair of tensors

A &algmult B - multiply two vectors in an algebra  

Parameters

A, B

-

Maple expressions, differential forms or tensors

Description

• 

In the DifferentialGeometry package the wedge product of 1-forms is defined in terms of the tensor product by α⁢∧β⁢=⁢α⁢⊗⁢β⁢−⁢β⁢⊗α.

• 

When using these commands together within a single Maple expression, it is important to use parentheses to insure that the operations are executed in the correct order.

• 

In an interactive Maple session, it is usually more convenient to use the commands evalDG and DGzip to perform these basic algebraic operations.

• 

Here are the precise lists of admissible arguments for these commands.

• 

A &plus B, A &minus B -- A and B: Maple expressions, vectors, differential forms of the same degree, differential biforms of the same bidegree, tensors with the same index type and density weights. A and B must be defined on the same frame.

• 

A &mult B -- A: a Maple expression; B: a Maple expression, vector, differential form, differential biform, tensor. A and B must be defined on the same frame.

• 

A &wedge B -- A and B: Maple expressions or differential forms, differential biforms.  If A and B are forms, then the sum of their degrees cannot exceed the dimension of the frame on which they are defined. If A and B are bi-forms, then the sum of their horizontal degrees cannot exceed the dimension of the base manifold on which they are defined.  A and B must be defined on the same frame.

• 

A &tensor B -- A and B: Maple expressions, vectors, differential 1-forms, tensors.  A and B must be defined on the same frame.

• 

These commands are part of the DifferentialGeometry package, and so can be used in the forms given above only after executing the command with(DifferentialGeometry).

Examples

> 

with⁡DifferentialGeometry:with⁡LieAlgebras:

 

Use DGsetup to define a three-dimensional manifold M with coordinates [x, y, z].

> 

DGsetup⁡x,y,z,M,verbose

The following coordinates have been protected:

x,y,z

The following vector fields have been defined and protected:

D_x,D_y,D_z

The following differential 1-forms have been defined and protected:

dx,dy,dz

frame name: M

(1)

 

Example 1.

Create linear combinations of vector fields and differential 1-forms using &plus and &mult.

> 

X1≔D_x&plusD_z

X1≔D_x+D_z

(2)
> 

X2≔3⁢z&multD_x&plus−2⁢y&multD_y

X2≔3⁢z⁢D_x−2⁢y⁢D_y

(3)
> 

X3≔X2&minus3⁢z&multX1

X3≔−2⁢y⁢D_y−3⁢z⁢D_z

(4)
> 

α1≔sin⁡z&multdx&minuscos⁡y&multdz

α1≔sin⁡z⁢dx−cos⁡y⁢dz

(5)
> 

α2≔cos⁡x&multdy&pluscos⁡z&multdz

α2≔cos⁡x⁢dy+cos⁡z⁢dz

(6)

 

Example 2.

Create differential 2-forms using &plus and &mult and &wedge.

> 

α3≔2&multdx&wedgedy&plus5&multdy&wedgedz

α3≔2⁢dx⁢⋀⁢dy+5⁢dy⁢⋀⁢dz

(7)
> 

α4≔α1&wedgeα2

α4≔sin⁡z⁢cos⁡x⁢dx⁢⋀⁢dy+sin⁡2⁢z⁢dx2⁢⋀⁢dz+cos⁡y⁢cos⁡x⁢dy⁢⋀⁢dz

(8)
> 

α5≔α1&wedgeα2&minusα3

α5≔−2+sin⁡z⁢cos⁡x⁢dx⁢⋀⁢dy+sin⁡2⁢z⁢dx2⁢⋀⁢dz+−5+cos⁡y⁢cos⁡x⁢dy⁢⋀⁢dz

(9)
> 

α6≔α1&wedgeα3

α6≔−2⁢cos⁡y−5⁢sin⁡z⁢dx⁢⋀⁢dy⁢⋀⁢dz

(10)

 

Example 3.

Create various tensors using &plus, &mult and &tensor.

> 

T1≔X1&tensorX1

T1≔D_x⁢D_x+D_x⁢D_z+D_z⁢D_x+D_z⁢D_z

(11)
> 

T2≔X1&tensorα1

T2≔sin⁡z⁢D_x⁢dx−cos⁡y⁢D_x⁢dz+sin⁡z⁢D_z⁢dx−cos⁡y⁢D_z⁢dz

(12)
> 

T3≔1&tensordx&wedgedy

T3≔dx⁢dy−dy⁢dx

(13)
> 

T4≔dx&tensordx&tensorD_y&tensorD_z&tensordz

T4≔dx⁢dx⁢D_y⁢D_z⁢dz

(14)
> 

T5≔1y2&multdx&tdx+dy&tdy

T5≔dxy2⁢dx+dyy2⁢dy

(15)

 

Example 4.

Create a multi-vector using &plus, &mult and &tensor.

> 

V1≔2&multD_x&wedgeD_y&plus3&multD_y&wedgeD_z

V1≔2⁢D_x⁢⋀⁢D_y+3⁢D_y⁢⋀⁢D_z

(16)

Example 5.

Use the command AlgebraLibraryData to retrieve the structure equations for the quaternions.

> 

LA≔AlgebraLibraryData⁡Quaternions,Q

LA≔e12=e1,e1·e2=e2,e1·e3=e3,e1·e4=e4,e2·e1=e2,e22=−e1,e2·e3=e4,e2·e4=−e3,e3·e1=e3,e3·e2=−e4,e32=−e1,e3·e4=e2,e4·e1=e4,e4·e2=e3,e4·e3=−e2,e42=−e1

(17)

Initialize.

> 

DGsetup⁡LA,e,i,j,k,θ

algebra name: Q

(18)

Calculate some simple sums and products of quaternions.

> 

Q1≔i&algmultj

Q1≔k

(19)
> 

Q2≔e&plusi&plusj&plusk&algmulte&minusi&plusj&plusk

Q2≔4⁢e

(20)

See Also

DifferentialGeometry

DGzip

evalDG